The present invention relates to a motor-driven compressor having an electric motor, a compression mechanism and an inverter aligned in a housing in axial direction of a rotary shaft of the compressor.
In such compressor, the motor is controlled by the inverter. The motor needs to be supplied with a large amount of power from the inverter to operate the compression mechanism. In the inverter, switching operation of switching devices (heat-generating components) is frequently performed, so that a large amount of heat is generated. Therefore, cooling of the inverter is required in such compressor in order to maintain the proper operation of the inverter.
A compressor with a cooling mechanism for the inverter is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2001-263243. The compressor includes a hermetic housing of a cylindrical shape. The housing accommodates therein a compression mechanism, a motor, and a rotary shaft coupling the compression mechanism to the motor. The compression mechanism, the motor and the rotary shaft are aligned in the longitudinal direction of the housing. The housing is formed with a cylindrical heatsink for cooling the inverter. The heatsink is provided integrally at the housing end adjacent to the motor. The heatsink is formed at the outer periphery thereof with a plurality of flat mount surfaces. Heat-generating components of the inverter are fixedly mounted on such mount surfaces so that the heat transfer is allowed. The heatsink and the inverter are covered with a protector. The heatsink is disposed so as to extend over the entire axial length of the inner space of the protector, and the inverter is located between the heatsink and the protector.
In the compressor, while the inverter supplies power to the motor, heat is generated in the inverter. The heat is transferred to the heatsink and radiated into the atmosphere. The heat is also transferred from the heatsink to the housing and radiated. Since the heat transferred to the heatsink is absorbed by refrigerant flowing through the inner space of the heatsink, the heat is efficiently radiated. As a result the inverter is cooled.
In the compressor, however, since the heatsink is disposed so as to extend over the entire axial length of the inner space of the protector, arrangement of the inverter in the space of the protector is not flexible. In addition, the shape of a circuit board of the inverter is also not flexible, accordingly inverter design is not flexible.
The present invention is directed to providing a motor-driven compressor with improved efficiency of cooling of heat-generating components and is expanded inverter design freedom.